Orogenic Au deposits represent one of the largest sources of gold in the world and in Brazil, particularly at the Quadrilátero Ferrífero, southeastern portion of the São Francisco Craton. In the last decades, advances in in-situ analytical techniques allowed a detailed investigation of the chemistry of sulfides. This can reveal information about the origin and composition of the mineralizing fluids, potential sources of metals and sulfur and the fluid-rock interaction during the ore-forming processes. In this paper we combine Electron Microprobe Analysis and LA-ICP-MS analyses to put constraints on the nature and evolution of the Pitangui gold deposit. The Pitangui deposit represents an important Orogenic Au deposit hosted in clastic metasedimentary rocks of the Pitangui greenstone belt, northwestern portion of the Quadrilátero Ferrífero. Detailed drill hole, petrographic observations and in-situ chemical analyses of the hydrothermal alteration zones show that pyrite is the dominant ore mineral in the deposit and two possible origins are suggest including (i) syngenetic pyrite development at the early stages of the greenstone belt evolution and (ii) epigenetic pyrite, which is associated with hydrothermal processes during the Orogenic Au event. Syngenetic pyrite (PyI) has high Co, Bi, Pb, Sb, Te, Se, Ag and Au concentrations. The PyI could represent an important source of metals, a set of trace elements and likely sulfur for the later Orogenic Au mineralization. Epigenetic pyrites (PyII, PyIII and PyIV), conversely, are mainly found in association with hydrothermal minerals and within the mineralized carbonate-quartz-vein. The variations at Co, Ni, Pb, Te, Sn, Se, As, Bi, Sb, Ag, Mo and W in the epigenetic pyrite indicate that the dehydration PGB sequences during orogenesis constitutes the main fluids sources. The PyV, in turn, only appears at metamafic dyke, but its origin remains unclear.

造山金矿床是世界和巴西最大的黄金来源之一，尤其是在圣弗朗西斯科克拉通东南部的 Quadrilátero Ferrífero。在过去的几十年里，原位分析技术的进步允许对硫化物的化学进行详细研究。这可以揭示有关矿化流体的来源和组成、金属和硫的潜在来源以及成矿过程中流体-岩石相互作用的信息。在本文中，我们结合电子微探针分析和 LA-ICP-MS 分析来限制 Pitangui 金矿床的性质和演化。Pitangui 矿床是一个重要的造山金矿床，位于 Quadrilátero Ferrífero 西北部 Pitangui 绿岩带的碎屑变沉积岩中。对热液蚀变带的详细钻孔、岩相观察和原位化学分析表明，黄铁矿是该矿床中的主要矿石矿物，并提出了两个可能的成因，包括 (i) 绿岩带演化早期的同生黄铁矿发育(ii) 后生黄铁矿，它与造山金事件期间的热液过程有关。同生黄铁矿 (PyI) 具有较高的 Co、Bi、Pb、Sb、Te、Se、Ag 和 Au 浓度。PyI 可以代表金属、一组微量元素和可能用于后期造山金矿化的硫的重要来源。相反，后生黄铁矿（PyII、PyIII 和 PyIV）主要与热液矿物结合并在矿化碳酸盐石英脉中发现。Co、Ni、Pb、Te、Sn、Se、As、Bi、Sb、Ag、后生黄铁矿中的 Mo 和 W 表明造山过程中的脱水 PGB 序列构成了主要的流体来源。反过来，PyV 只出现在变质岩脉中，但其起源仍不清楚。